The following questions are from the California Achievement Test, and were written to test third graders' English language 'achievement.' Tests like this one are used to determine things from what kind of funding a school gets to whether a particular child is marked as 'learning disabled.' The instructions asked the student to pick the answer that "you think is correct."

1) Beth _______ home and cried. a. come b. came

2) Can you ________ out now? a. went b. go

3) When _______ I come again? a. can b. may

What do these questions test? A variety of different things, really. Take question 1, to start with. The correct answer to this question (according to the test makers) is b., Beth came home and cried. But to speakers of several vernacular dialects in which the "bare root form" of come is used as an irregular past tense form, the more natural, grammatically correct answer is a., Beth come home and cried.

What is defined as 'correct' by the people who made this test is using the standard dialect as opposed to the non-standard dialect. For a speaker of Standard American English, this is a very easy question to get right: all you do is, as the instructions say, pick the answer that "you think is correct." But for a speaker of a dialect in which come is an acceptable answer, it's significantly trickier: you must be aware that the standard form of the past tense of come is came, even though that is not how you would say it, and you must be able to recognize this as a situation where, regardless of what the instructions say, you should go against instinct and pick the standard form. Some nine-year-olds can do that, but many will have trouble.